New Robot Crawls Like an Earthworm

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Dubbed the "Meshworm," a new bio-inspired robot stretches and
contracts to crawl across the ground like an earthworm. But
unlike its living, breathing counterpart, this artificial
creature is durable enough to survive being bludgeoned by a
hammer.

"You can throw it, and it won't collapse. Most mechanical parts
are rigid and fragile at small scale, but the parts in Meshworms
are all fibrous and flexible," said mechanical engineering
researcher Sangbae Kim in a statement from MIT. "The muscles are
soft, and the body is soft … we're starting to show some
body-morphing capability."

Earthworms
have two muscle groups in their bodies that work together to help
it move on the ground. Circular muscle fibers that wrap around
the worm's tubular body move it forward and muscle fibers that
run along the worm's length move it right and left.

The researchers tried to imitate this structure for their robot.
They made a long tube-like body with a sheet of flexible polymer
mesh and created artificial muscles with a nickel-titanium alloy.
Like the earthworm's muscles, some of these metal wires were
coiled around the robot while others spanned its body from front
to back, the statement from MIT said. [ See
Earthworm-Robot Video ]

A small battery and circuit board was added to the tube to
produce a current to heat the wires at certain segments along the
body. Heat causes the "muscles" to contract and the researchers
developed algorithms to control the wires' heating and cooling,
directing different patterns of movement.

Though small, the Meshworm is durable. The robot squirmed away
unscathed after being stepped on, thrown and hit with a hammer,
the researchers said. They believe
soft robots like the Meshworm might be able to
explore tight spaces and travel easily over bumpy terrain.
The model could even have applications in electronics,
endoscopes, implants and prosthetics.

"Even though the robot’s body is much simpler than a real worm —
it has only a few segments — it appears to have quite impressive
performance," Kellar Autumn, of Lewis and Clark College, said in
the statement from MIT. "I predict that in the next decade we
will see shape-changing artificial muscles in many products, such
as mobile phones, portable computers and automobiles."

Details of the design were published in the journal Transactions
on Mechatronics.